This invention relates to tamper-resistant, tamper-evident composite lids for containers for products presenting significant concerns for the consumer about unauthorized tampering with the product (e.g. food products and other consumables) or unintended release of the product (e.g. hazardous chemical compositions).
By a xe2x80x9ccompositexe2x80x9d lid, is meant a lid composed of a sheet of printed matter (e.g. paperboard) serving as the cover top panel and a molded plastic rim bonded to and compatible with the panel material to form the means for engaging the lid to the container. U.S. Pat. No. 6,053,353 (Helms) exemplifies a composite container closure of this kind. Where they are capable of being used instead of wholly plastic lids, composite lids allow for reduced material costs and superior lid-top graphics.
In recent years, concerns have increased surrounding potential and actual incidents of malicious contamination of packaged foods and medicine.
Preventive measures taken in the packaging of non-prescription analgesic medicine are well know. A number of tamper-resistant closures have also been introduced for screw-cap bottles, as in U.S. Pat. No. 4,394,918 (Grussen). Tamper-resistant push-on cap assemblies for re-usable glass bottles (e.g. milk bottles) are described in U.S. Pat. Nos. 5,875,908 (Witt et al) and 6,341,707 (Witt et al), owned in common with the present application.
In the ice cream packaging industry, a variety of closure arrangements are used to hold a paperboard, plastic or composite lid in place on the paperboard container or tub holding the ice cream. None of the ice cream containers currently in use employs the sort of protection against tampering that is common in other types of food packaging. A chief reason for this lies in the increased cost in including a tamper-evident feature in the lid, as well as the limited space available in processing plants for equipment which would apply such a feature.
A small segment of the ice-cream production market does make use of a heat-sealed film over the container opening, but this is far from satisfactory from the aspect of clearly indicating any post-packaging tampering with the product.
It is of great and increasing importance that the consumer, at the point of purchase of a product, be confident that the package that he or she intends to purchase has not been compromised. If there is a problem with the packaging which can not be spotted until the consumer opens it for use, he or she may well never purchase that product again and consumer confidence is reduced generally.
It is a general object of the invention to provide a composite container closure member that can be used to resist and to render readily detectable tampering of the products at the point of sale. Particular examples include dairy products, cosmetics, granular or powdered food products such as tubs for bread crumbs, hardware product tubs for screws, nuts and bolts, and so on.
It is a particular object of the present invention to provide a tamper-resistant tamper-evident lid for ice cream and other dairy products that is commercially practical and provides the level of tamper evidence needed for food safety.
With a view to these and other objects the present invention provides a closure made of economical raw materials, which may be applied to the container at the time of packaging using existing capping equipment with minor modifications that require no additional operating space. The present invention provides a new and improved composite lid for containers of the kind having an opening with a peripheral lip formation, such as a standard ice cream container.
A tamper-evident container closure member according to the present invention comprises an outer cylindrical ring portion having an upper peripheral margin and a lower peripheral margin and an inner cylindrical ring portion having a lower peripheral margin which extends vertically below that of the outer cylindrical ring and an upper peripheral margin integrally connected to the outer cylindrical ring portion by an annular ledge formation that serves as the seat for a central top panel formed from a blank of generally flexible sheet material.
At a vertical position intermediate the lower peripheral margin of the outer cylindrical ring portion and its own lower peripheral margin, the inner cylindrical ring portion is circumscribed by a rupturable line of weakness formed, for example, by thinning the plastic material along an inner circumferential line.
A plurality of resiliently deformable teeth extend upwardly and inwardly from the lower peripheral margin of the inner cylindrical ring portion of the closure. These teeth are configured for engagement of the lip of a container when the closure member is in place.
The top panel of the lid is typically of waterproofed paperboard or like material bearing the desired graphics on the outside and is sealed against the annular ledge that connects the outer to the inner ring portion of the closure. Preferably, the upper edge surface of this ledge is downwardly recessed relative to the upper peripheral margin of the outer ring, to prevent manual access to the peripheral edge of the cover panel.
When the lid is pushed on to the container having a lip about the top opening, the teeth on the inner ring portion lock on to the container lip. Rupture of the inner ring along the line of weakness permits removal of the rest of the lid closure with cover panel, to open the container, while the tamper-evidencing lower portion of the inner ring can simply be pulled away from the container and disposed of by the consumer.